Translation guide
Expresses that something is resistant to water, does not let water in, or is suitable for use in wet conditions. Japanese uses different words depending on whether you mean a material, a watch, clothing, or making something waterproof.
Describing an item or material that resists water penetration, often used for watches, electronics, and outdoor gear.
The most common and general term for 'waterproof' or 'water-resistant'. Used as a noun or adjective (often with の). Appears on product labels.
この時計は防水です。
This watch is waterproof.
防水加工のジャケット
a waterproof jacket
Literally 'water-resistant'. Often used in technical contexts or for materials that withstand water to some degree, but may not be fully submersible.
耐水性能をテストする
to test waterproof performance
Specifically for garments that keep rain out, like raincoats or rain boots.
A raincoat. The most natural way to refer to a waterproof coat.
雨が降りそうだからレインコートを持っていこう。
It looks like rain, so let's take a raincoat.
A traditional or casual raincoat, often made of vinyl or rubber. Slightly old-fashioned or used for children's rainwear.
Rain boots, waterproof footwear.
レインブーツを履いて出かける。
Go out wearing rain boots.
The action of treating something to make it waterproof.
To apply waterproofing treatment. A formal or technical phrase.
テントに防水加工を施した。
I waterproofed the tent.
A simpler verb form meaning 'to waterproof'. Less common than the noun form but understandable.
このスプレーで靴を防水できる。
You can waterproof your shoes with this spray.
Completely impervious to water, often used in science or engineering.
Impermeability to water. A technical term used in geology, civil engineering, etc.
この層は不透水性がある。
This layer is impermeable to water.
In Japanese, 防水 (bōsui) is often used for both 'waterproof' and 'water-resistant'. For 'water-repellent' (surface treatment that makes water bead up), 撥水 (はっすい, hassui) is more precise. If you need to distinguish, use 撥水 for water-repellent and 防水 for waterproof.
When describing an item, you can say 防水の + noun (e.g., 防水のバッグ) or simply use 防水 as a prefix (防水バッグ). Both are natural.
子供に雨合羽を着せる。
Put a raincoat on the child.